The top lever was not designed as a dial indicator arrow. That it can show wear to the mechanism as it moves left doesn't necessarily mean that 'left of center' is bad and worn out.
Check the bbls for any off the face movement with the action closed tightly (forend off) and the action locked and also with the action unlocked but the bbls held closed by hand.
The latter is helped if you hold the gun upside down and let the weight of the bbls hold themselves shut. Check for side to side movement, ect.
Top lever scratching the top tang is the lever being bent downward a little. Some are fitted very closely to the tang surface.
Some heavy handed handling with the lever open can usually bend most of them even if just a little. When they close after that,,they scrape the top tang.
Bending it back up, the simple bench method is to place a cardboard shim under the lever at the thumb piece. A business card folded if needed will usually do or a match book cover.
Then a light educated ping with a rawhide mallet or other non-marking hammer up close to the spindle will bounce the lever back up into position. Sounds barbaric, but that's the way it's done.
Trying to pry or bend it by grasping onto the thumbpiece end and levering it upwards back into position usually results in a bend w/a crimp in the lever up near the spindle where it's generally thinnest.
